Golf club head with improved inertia performance

ABSTRACT

A golf club head that is capable improving on the inertia properties of a golf club head all while also improving the Center of Gravity (CG) location is disclosed herein. More specifically, the golf club head in accordance with the present invention achieves a relative low Moment of Inertia (MOI) about the Z-axis (MOI-Z) as well as a relatively low MOI about the Shaft-axis (MOI-SA), all combined with a high MOI about the X and Y-axis (MOI-X and MOI-Y) and maintaining a consistently and relatively low CG location measured along a direction tangent to the hosel axis along the X-Y plane (CG-B).

FIELD OF THE INVENTION

The present invention relates generally to a new and improved golf club having improved Moment of Inertia (MOI) characteristics, combined with an improved Center of Gravity (CG) location. More specifically, the golf club head in accordance with the present invention achieves a relative low Moment of Inertia (MOI) about the Z-axis (MOI-Z), a low MOI about the Shaft Axis (MOI-SA), all combined with a high MOI about the X and Y-axis (MOI-X and MOI-Y) and maintaining a consistently and relatively low CG location measured along a direction tangent to the hosel axis along the X-Y plane (CG-B).

BACKGROUND OF THE INVENTION

With the development of the modern day oversized metalwoods, the performance capabilities of these types of golf clubs have increased dramatically over their predecessor, “the persimmon wood”. One of the ways these metalwood type golf clubs have been performing better than their predecessors is in the increase in overall distance, generally attributed to the inherent elastic deformation of thin metallic metal materials used by these metalwoods. Another way the metalwood type golf clubs have been outperforming their predecessors is in the increase in overall forgiveness of the golf club head, generally attributed to the increase in the MOI of the golf club head itself.

The MOI of a golf club head generally is a term used to describe the ability of an object to resist rotational movement upon impact with a secondary object. In the case of a golf club head, MOI refers to the ability of the golf club head to resist undesirable twisting upon impact with a golf ball, as such a twisting movement will generally change the face angle of the golf club head away from the intended target line, sending the golf ball away from the intended target.

U.S. Pat. No. 5,354,055 to MacKeil shows one of the earliest attempts to increase the MOI of a golf club head by placing the Center of Gravity (CG) location rearward. U.S. Pat. No. 6,364,788 to Helmstetter et al. shows the utilization of weighting members to help control the MOI of the golf club head. Both of these patents refer to the MOI-y of the golf club head, as it relates to the ability of the golf club head to stay stable when encountering an off-center impact in the heel and toe direction.

U.S. Pat. No. 7,850,542 to Cackett et al. illustrates a further development in the MOI research wherein a recognition of the different axis of rotation of the different MOI's. (Alternatively known as Ixx, Iyy, and Izz instead of MOI-X, MOI-Y, and MOI-Z) Despite the recognition and identification of the difference in MOI values, U.S. Pat. No. 7,850,542 only focuses its attention on Ixx and Iyy (adapted and changes to the current reference nomenclature), without any recognition of the importance of the last MOI number, Izz, nor MOI-SA and how they can affect the performance of the golf club.

Despite the above, none of the references recognizes the importance of the MOI of the golf club head horizontally forward and aft of the face (MOI-Z), and ways to design a golf club that takes advantage of the performance characteristics of golf club with more optimal MOI-Z values along with the minimized MOI-Sa values. Moreover, a closer investigation of the MOI-Z values will yield CG locations that will work in conjunction with the above MOI-Z values to create more performance. Hence, it can be seen from the above there is a need for more research and a design of a golf club capable of achieving better performance by investigating the importance of MOI-Z and MOI-SA as well as the CG location and designing a golf club head.

BRIEF SUMMARY OF THE INVENTION

One aspect of the present invention is a golf club head comprising of a frontal portion further comprising a striking face that defines a face center, located at a forward portion of the golf club head; a rear portion located aft of the striking face; and at least one weighting member located near a central portion of the golf club head in a heel to toe orientation, substantially in line with and behind the face center; wherein an x-axis is defined as a horizontal axis tangent to a geometric center of said striking face with the positive direction towards a heel of said golf club head, a y-axis is a horizontal axis orthogonal to said x-axis with a positive direction towards a crown of said golf club head, and a z-axis being orthogonal to both said x-axis and said y-axis with a positive direction towards a frontal portion of said golf club head, and wherein said golf club head has a MOI-Y to MOI-Z ratio of greater than about 1.50.

In another aspect of the present invention is a golf club head comprising of a golf club head comprising of a frontal portion further comprising a striking face that defines a face center, located at a forward portion of the golf club head, a rear portion located aft of the striking face, and at least one weighting member located near a central portion of the golf club head in a heel to toe orientation, substantially in line with and behind the face center; wherein an x-axis is defined as a horizontal axis tangent to a geometric center of said striking face with the positive direction towards a heel of said golf club head, a y-axis is a horizontal axis orthogonal to said x-axis with a positive direction towards a crown of said golf club head, and a z-axis being orthogonal to both said x-axis and said y-axis with a positive direction towards a frontal portion of said golf club head, and wherein said golf club head has a MOI-X, MOI-Z, and CG-Z numbers that satisfies the equation

$\frac{{MOI} - X}{{MOI} - Z} \geq {\left( {{6.7501*{CG}} - Z} \right) - {99.30.}}$

These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages of the invention will be apparent from the following description of the invention as illustrated in the accompanying drawings. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention.

FIG. 1 of the accompanying drawings shows a perspective view of a golf club head in accordance with an exemplary embodiment of the present invention;

FIG. 2 of the accompanying drawings shows a top view of a golf club head in accordance with an exemplary embodiment of the present invention;

FIG. 3 of the accompanying drawings shows a frontal view of a golf club head in accordance with an exemplary embodiment of the present invention;

FIG. 4 of the accompanying drawings shows a plot of MOI-Z vs MOI-Y numbers for the current invention, compared to prior art golf club heads;

FIG. 5 of the accompanying drawings shows a plot of MOI-Z vs MOI-Shaft Axis numbers for the current invention, compared to prior art golf club heads;

FIG. 6 of the accompanying drawings shows a plot of MOI-Y vs MOI-Shaft Axis numbers for the current invention, compared to prior art golf club heads;

FIG. 7 of the accompanying drawings shows a plot of MOI-X vs MOI-Shaft Axis numbers for the current invention, compared to prior art golf club heads;

FIG. 8 of the accompanying drawings shows a plot of MOI-Z vs CG-B/Face Width numbers for the current invention, compared to prior art golf club heads;

FIG. 9 of the accompanying drawings shows a plot of MOI-Z vs CG-B/Head Width numbers for the current invention, compared to prior art golf club heads;

FIG. 10 of the accompanying drawings shows a plot of MOI-X/MOI-Z vs CG-Z numbers for the current invention, compared to prior art golf club heads;

FIG. 11 of the accompanying drawings shows a plot of MOI-Y/MOI-Z vs CG-Z numbers for the current invention, compared to prior art golf club heads;

FIG. 12 of the accompanying drawings shows a plot of (MOI-X+MOI-Y)/MOI-Z vs CG-Z numbers for the current invention, compared to prior art golf club heads;

FIG. 13 of the accompanying drawings shows an exploded sole perspective view of a golf club head in accordance with an exemplary embodiment of the present invention;

FIG. 14 of the accompanying drawings shows a horizontal cross-sectional view of a golf club head in accordance with an exemplary embodiment of the present invention;

FIG. 15 of the accompanying drawings shows a vertical cross-sectional view of a golf club head in accordance with an exemplary embodiment of the present invention;

FIG. 16 of the accompany drawings shows a perspective view of a golf club head in accordance with an alternative embodiment of the present invention;

FIG. 17 of the accompanying drawings shows a top view of a golf club head in accordance with an alternative embodiment of the present invention;

FIG. 18 of the accompanying drawings shows a frontal view of a golf club head in accordance with an alternative embodiment of the present invention;

FIG. 19 of the accompanying drawings shows a horizontal cross-sectional view of a golf club head in accordance with an alternative embodiment of the present invention; and

FIG. 20 of the accompanying drawings shows a vertical cross-sectional view of a golf club head in accordance with an alternative embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description describes the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.

Various inventive features are described below and each can be used independently of one another or in combination with other features. However, any single inventive feature may not address any or all of the problems discussed above or may only address one of the problems discussed above. Further, one or more of the problems discussed above may not be fully addressed by any of the features described below.

Before beginning the discussion on the current inventive golf club head and its performance criteria, it is worthwhile to note here that the discussion below will be based on a coordinate system 101 and axis of measurement that is critical to the proper valuation of the performance numbers. Hence, it is important to recognize here that although the specific names given for the measurements below are important to the understanding of the current invention, the naming nomenclature should not be viewed in vacuum. Rather, the importance is the numbers presented below needs to be taken in context with how the coordinate system relates to the golf club head itself. In order to provide sufficient information to avoid any ambiguity, each of the figures provided below referencing a golf club head will all be accompanied by a coordinate system that is all consistent with one another.

Pursuant to the above, and to establish the reference coordinate system for the subsequent discussion, FIG. 1 of the accompanying drawings shows the coordinate system 101 that will be used to define the various measurement and performance figures for the current invention. The x-axis used by the current discussion refers to the axis that is horizontal to the striking face from a heel to toe direction. The y-axis used by the current discussion refers to the vertical axis through the club in a crown to sole direction. The z-axis used by the current discussion refers to the horizontal axis that is horizontal front to back in a forward and rear direction. Alternatively speaking, it can be the x-axis is defined as a horizontal axis tangent to a geometric center of the striking face with the positive direction towards a heel of the golf club head, a y-axis is a horizontal axis orthogonal to the x-axis with a positive direction towards a top of the golf club head, and a z-axis being orthogonal to both the x-axis and the y-axis with a positive direction towards a front of the golf club head. The x-y-z coordinate system described above shall be the same for all subsequent discussions.

FIG. 1 of the accompanying drawings shows a perspective view of a golf club head 100 in accordance with an embodiment of the present invention. In this perspective view shown in FIG. 1, the golf club head 100 may not look very different than other golf club heads, but the subsequent figures and discussion will show that the internal components and the material properties of this golf club head 100 allows it to achieve unique performance properties consistent with the present invention. What FIG. 1 does show is a location of a face center 102 of the frontal portion 104 of the golf club head 100 that contains a striking face insert. The face center, as shown here and referred to by the current invention, relates to the geometric center of the striking face portion of said golf club head 100 measured by the USGA provided face center template as it would be commonly known to a person of ordinary skill in the golf club art. Attached to the rear of the frontal portion 104 is a rear portion 106, which makes up the back end of the golf club head 100.

In this embodiment of the present invention, the frontal portion 104 may generally be made out of a steel type material having a density of between about 7.75 g/cc and about 8.00 g/cc, allowing a significant portion of the mass of the golf club head 100 to be concentrated at a frontal bottom region of the golf club head 100. The rear portion 106 of the golf club head 100 in this embodiment of the present invention may generally be made out of the standard titanium material having a density of between about 4.00 g/cc and about 5.00 g/cc, allowing the rear portion 106 of the golf club head 100 to be relatively lightweight. However, it should be noted that in alternative embodiments of the present invention, the frontal portion 104 may also be made out of a standard titanium material such as TI-6-4, Ti-8-1-1, SP-700, or any other type of titanium material without departing from the scope and content of the present invention.

In order to illustrate more specific features of the golf club head 100, FIGS. 2 and 3 of the accompanying drawings is provided to give more insight into some of the specific inherent characteristics of the golf club head 200 that will be important to determine its improved performance. First off, FIG. 2 of the accompanying drawings, in addition to illustrating a golf club head 200 with a frontal portion 204 and a rear portion 206, also shows a Center of Gravity (CG) 210 location along the x-z plane on the coordinate system 201. Although the details of the CG location will be discussed in more detail with respect to the inertia properties of the golf club head 200, the general direction of the current inventive golf club head 200 is to have a CG location that is strategically located at a distance back from the frontal portion of the golf club head 200 to yield the most advantageous results.

More specifically, in the current invention, the CG location rearward from the striking face, identified here as CG-Z is generally between about 25 mm to about 40 mm, more preferably between about 26 mm and about 38 mm, and most preferably between about 27 mm and about 36 mm, all measured rearward from the face center 202 along the Z axis shown by the coordinate system 201. In addition to illustrating the CG-Z 212 numbers, an alternative measurement method is provided to measure how far back the CG 210 is located within the club head 200. In this alternative method, the CG 210 is measured from the shaft axis 215, and this measurement is illustrated as CG-C 214 is generally measured to be between about 10 mm to about 25 mm, more preferably between about 12 mm to about 23 mm, and most preferably between about 14 mm to about 21 mm, all measured rearward from the shaft axis 215 along the Z axis shown by the coordinate system 201.

It should be noted that the strategic location of the CG 210 location rearward along the Z axis, irrespective of whether it is measured from the face center 202 or the shaft axis 215, is critical to the proper functionality of the current inventive golf club head 200. If the CG 210 location is too far forward, the golf club head 200 can result in a low MOI-X and MOI-Y as well as too low of a backspin when contacting a golf ball to yield desirable results. However, in the alternative, if the CG 210 location is too far rearward, the golf club head 200 can produce too much spin to yield desirable results. Hence, it can be seen that the criticality of the CG location rearward of along the Z axis is a fine balance of a very specific range of numbers that can severely hinder the performance of the golf club head 200 if it deviates from the ranges articulated above.

FIG. 3 of the accompanying drawings shows another important CG 210 measurement that is important to the proper functionality of the current invention. More specifically, FIG. 3, in addition to illustrating all of the basic components of the golf club head 200 as previously shown, now introduces another measurement of the CG 210 location from the shaft axis 215 along an x-y plane shown by coordinate system 301. More specifically, FIG. 3 shows a CG 210 measurement that is perpendicular to the shaft axis 215 along this x-y plane away from the actual shaft axis 215 itself, called CG-B for the purpose of this application. The CG-B of the golf club head 210 may generally be between about 32 mm and about 39 mm, more preferably between about 33 mm and about 38 mm, and most preferably about 35 mm.

In addition to illustrating the very important CG-B measurement of the golf club head, FIG. 3 of the accompanying drawings also shows measurements W1 and W2, indicative of the width of the golf club head 200 itself and the width of the face of the golf club head 200 respectively. In this embodiment of the present invention, the width of the golf club head W1 may generally be between about 130 mm to and about 140 mm, more preferably between about 132 mm to about 138 mm, and most preferably about 136 mm. The width of the face W2 may generally be between about 95 mm and about 105 mm, more preferably between about 97 mm and about 103 mm, and most preferably about 100 mm.

Now that the CG location of the golf club head 200 has been defined, the other important features associated with the present invention relates to the Moment of Inertia (MOI) of the golf club head 200. The MOI of a golf club head generally depicts the ability of the golf club head to resist twisting when it impacts an object at a location that is not aligned with the CG location previously discussed. More specifically, the MOI of a golf club head relates to the ability of the golf club head to resist twisting relative to the CG location. The MOI of the golf club head 200 may generally be broken down to three unique components, relating to the ability of the golf club head 200 to resist rotation along three different axes. The three axes of rotation for which the MOI is generally referred coincides with the coordinate system 101, 201, and 301 (shown in FIG. 1, FIG. 2, and FIG. 3 respectively).

As the previously discussion already hinted, the current inventive golf club head 200 may generally have a high value for the MOI about the X and Y axis, while maintaining a low MOI about the Z axis. More specifically, the current inventive golf club head 200 may generally have a MOI about the X axis (MOI-X) that is greater than about 300 kg-mm², more preferably greater than about 310 kg-mm², and most preferably greater than about 320 kg-mm² without departing from the scope and content of the present invention. As for MOI about the Y axis (MOI-Y), the present inventive golf club head 200 may generally have a MOI about the Y axis that is greater than about 400 kg-mm², more preferably greater than about 410 kg-mm², and most preferably greater than about 420 kg-mm² all without departing from the scope and content of the present invention.

While the large MOI number about the X and Y axis discussed previously are not necessarily new in the world of golf club 200 designs, the ability to maintain those number while decreasing the MOI about the Z axis (MOI-Z) and holding the MOI about the Shaft axis (MOI-SA) to a minimum is what makes the present invention. While the majority of the golf industry are focusing their attention so intently on the ability of the golf club head 200 to offer forgiveness on off center hits by trying to increase the MOI-Y to astronomical numbers, they have failed to recognize the ability of the golf club head 200 to offer more club head speed and more ball speed by decreasing the MOI about the Z axis (MOI-Z) in concert with the minimization of MOI about the Shaft axis (MOI-SA). The present invention focuses its attention on that very specific unrecognized characteristic, and has developed a golf club head 200 design to take advantage and maximize the performance of the golf club head 200 by focusing on the MOI about the Z axis. More specifically, a golf club head 200 in accordance with the present invention may generally have a MOI about a Z axis that is less than about 268 kg-mm², more preferably less than about 260 kg-mm², and most preferably less than about 250 kg-mm². Additionally, the golf club head 200 may generally have a MOI about a Shaft axis that is less than about 850

It should be noted here that the low MOI-Z numbers mentioned above cannot by itself accurately depict and describe the current invention; as old school golf club heads with much smaller footprint may inherently have a low MOI-Z number, combined with a low MOI-X and MOI-Y number. Hence, it is important to recognize here that the present invention is predicated on the interrelationship between the different numbers achieved by the MOI-X and MOI-Y numbers as it relates to MOI-Z and MOI-SA, in combination with the CG location articulated above.

In order to capture the essence of the present invention, a ratio can be created between the MOI-X, MOI-Y, and MOI-Z to help provide one way to quantify this relationship. In one first example, a MOI-X to MOI-Z Ratio can be created to help quantify the current golf club head 200 as illustrated by Eq. (1) below. In one exemplary embodiment of the present invention, the MOI-X to MOI-Z Ratio is greater than about 1.10, more preferably greater than about 1.20, and most preferably greater than about 1.28.

$\begin{matrix} {{{MOI} - {X\mspace{14mu} {to}\mspace{14mu} {MOI}} - {Z\mspace{14mu} {Ratio}}} = \frac{{MOI} - X}{{MOI} - Z}} & {{Eq}.\mspace{14mu} (1)} \end{matrix}$

Similarly, a comparable ratio can be established called a MOI-Y to MOI-Z Ratio to quantify the current golf club head 200 as illustrate by Eq. (2) below. In one exemplary embodiment of the present invention, the MOI-Y to MOI-Z ratio is greater than about 1.50, more preferably greater than about 1.57, and most preferably greater than about 1.68.

$\begin{matrix} {{{MOI} - {Y\mspace{14mu} {to}\mspace{14mu} {MOI}} - {Z\mspace{14mu} {Ratio}}} = \frac{{MOI} - Y}{{MOI} - Z}} & {{Eq}.\mspace{14mu} (2)} \end{matrix}$

As it can be seen from the relationship established by the Eqs (1) and (2) above, the present invention relates to a specific relationship between the MOI of the golf club head 200 with an extra focus on minimizing the MOI-Z about the Z axis while maintaining a high MOI-Y. In order to further illustrate this, a graphical representation of the relationship is provided as FIG. 4.

FIG. 4 of the accompanying drawings shows a plot of various data points of various golf club head and their respective MOI-Z numbers as well as their MOI-Y number. In FIG. 4 the X-axis represents the MOI-Y while the Y-axis represents the MOI-Z. The data points shown in FIG. 4 have been separated into circular dots and asterisks. The circular dots are representative of the data of “prior art” golf club heads, whereas the asterisk data points represent the current invention.

A closer examination of the prior art data points will show that none of the golf club heads in the prior art are capable of achieving a MOI-Z number of lower than 268 kg-mm², for all modern day golf club heads that have a MOI-Y of greater than 420 kg-mm². However, an even closer examination of the graph of FIG. 4 will show that as the MOI-Y numbers of the golf club heads exceeds 500 kg-mm², an additional relationship can be established to quantify the ability of the present invention to achieve the optimal MOI-Z to MOI-Y relationship. In fact, that relationship is shown in FIG. 4 as Y≤0.47×+33. Combining the two conditions articulated above can result in another unique way to quantify the present invention whereas, for golf club heads having a MOI-Y of between 420 kg-mm² and 500 kg-mm², the golf club head generally has a MOI-Z of less than about 268; however, for golf club heads having a MOI-Y of greater than 500 kg-mm², the golf club head may have a MOI-Z that satisfies Eq. (3) below:

MOI-Z≤(0.47*MOI-Y)+0.33  Eq. (3)

Alternatively speaking, it can be said that in one embodiment of the present invention, the golf club head 200 may have a MOI-Z that satisfies the relationship MOI-Z≤(0.47*MOI-Y)+0.33 if the MOI-Y number is greater than 500 kg-mm², and a MOI-Z that is less than 268 kg-mm² if the MOI-Y number is between 420 kg-mm² and 500 kg-mm².

FIG. 5 of the accompanying drawing introduces another MOI value relating to a golf club head not previously discussed named MOI-Shaft Axis (MOI-SA). The MOI of a golf club head as it relates to the shaft axis is defined as the ability of the golf club head to resist twisting upon impact with a golf ball at a location that is not aligned with the shaft axis. A golf club head in accordance with the present invention may generally have a MOI-SA of less than about 850 kg-mm², more preferably less than about 800 kg-mm², and most preferably less than about 750 kg-mm². The relationship between the MOI-SA and MOI-Z is highlighted in FIG. 5 and is important to the present invention. FIG. 5 of the accompanying drawings shows that irrespective of the MOI-SA numbers, all of the prior art golf club heads have a MOI-Z of greater than about 268 kg-mm², while all of the current inventive golf club heads have a MOI-Z of less than about 268 kg-mm².

FIG. 6 of the accompanying drawings establishes a graphical relationship between the MOI-Y of the golf club head with the newly introduced MOI-SA. As a closer examination of the graph shown in FIG. 6 will show, the current invention is capable of achieving a higher than average MOI-Y, all while keeping a relatively small MOI-SA. Similar to previous plots, the circular points on the plot will refer to prior art golf club heads, while the asterisks will refer to the current invention. Hence, it can be seen that the present invention occupies a previously unachieved space delineated by an equation Y≥0.52×+147, which when put into context with the variables used in this plot, yields Eq. (4) below:

MOI-Y≥(0.52*MOI-SA)+147  Eq. (4)

FIG. 7 of the accompanying drawings establishes a graphical relationship between the MOI-X of the golf club head with now a familiar MOI-SA. As a closer examination of the graph shown in FIG. 7 will show, the current invention is capable of achieving a higher than average MOI-X, all while keeping a relatively small MOI-SA. Hence, it can be seen that the present invention occupies a previously unachieved space delineated by an equation Y≥0.40×+50, which when put into context with the variables used in this plot, yields Eq. (5) below:

MOI-X≥(0.40*MOI-SA)+50  Eq. (5)

FIG. 8 of the accompanying drawings establishes a graphical relationship between the MOI-Z of the golf club head with a ratio of CG-B/Face Width. Both the measurement for CG-B and Face Width can be found in FIG. 3 of the accompanying drawings as well as the accompanying discussion in paragraphs [0022] and [0023]. The CG-B measurement is explicitly shown in FIG. 3, while the Face Width referred to by the chart in FIG. 8 is shown as W2. A closer examination of the graph shown in FIG. 8 will show that the current invention is capable of achieving a lower MOI-Z, while keeping the CG-B/Face Width number fairly consistent above 0.4. CG-B/Face Width is indicative of the location of the center of gravity while keeping a moderately sized face golf club head.

In the chart shown in FIG. 8, it can be seen that the present invention occupies a previously unachieved space delineated by an equation Y≤1000×−150, which when put into context with the variable used in this plot, yields Eq. (6) below:

$\begin{matrix} {{{MOI} - Z} \leq {\left( {1000*\frac{{CG} - B}{{Face}\mspace{14mu} {Width}}} \right) - 150}} & {{Eq}.\mspace{14mu} (6)} \end{matrix}$

FIG. 9 of the accompanying drawings establishes a graphical relationship between the MOI-Z of the golf club head with a ratio of CG-B/Head Width. Both the measurement for CG-B and Head Width can be found in FIG. 3 of the accompanying drawings as well as the accompanying discussion above in paragraph [0022] and [0023]. The CG-B measurement is explicitly shown in FIG. 3, while the Head Width referred to by the chart in FIG. 9 is shown as W1. A closer examination of the graph shown in FIG. 9 will show that the current invention is capable of achieving a lower MOI-Z, while keeping the CG-B/Head Width number fairly consistent above 0.34. CG-B/Head Width is indicative of the location of the center of gravity while keeping a moderately sized head width of the golf club head.

In the chart shown in FIG. 9, it can be seen that the present invention occupies a previously unachieved space delineated by a MOI-Z number that is lower than 320 kg-mm² combined with a CG-B/Head Width number that is greater than about 0.34.

FIG. 10 of the accompanying drawings establishes another graphical relationship of the performance of a golf club in accordance with an embodiment of the present invention. More specifically, FIG. 10 of the accompanying drawings shows a relationship between MOI-X/MOI-Z and CG-Z. (MOI-X is used interchangeably with Ixx, MOI-Y is used interchangeably with Iyy, and finally MOI-Z is used interchangeably with Izz) The definition and measurement for CG-Z of a golf club head can be found in the earlier discussion relating to FIG. 2 of the accompanying drawings, while the background information establishing MOI-X and MOI-Z have already been discussed previously. Although the selection of the plot for the X and Y axis may appear random initially to a person not versed in golf club design, but a closer examination will reveal that the relationship created here is absolutely critical to the proper performance of the present invention. On the Y axis of the plot shown in FIG. 10, a ratio between MOI-X and MOI-Z is created here. This ratio created illustrates the ability of the current inventive golf club head to maximize the value of one variable (MOI-X) while minimizing the value of another variable (MOI-Z); which resonates with the theme of the present invention. The MOI-Z used in the X axis of the plot shown in FIG. 10 is indicative of the CG location of the golf club head rearward from the front of the golf club head, and it is desirable to maintain that in the range described above.

A further examination of the plot shown in FIG. 10 will show that the present invention occupies a portion of the graph that was previously unachieved. This portion of the graph is delineated from other prior art data points by an equation Y≥6.7501×−99.3, which when put into context with the variable used in this plot, yields Eq. (7) below:

$\begin{matrix} {\frac{{MOI} - X}{{MOI} - Z} \geq {\left( {{6.7501*{CG}} - Z} \right) - 99.30}} & {{Eq}.\mspace{14mu} (7)} \end{matrix}$

FIG. 11 of the accompanying drawings establishes another graphical relationship of a golf club in accordance with an embodiment of the present invention by creating a relationship between the MOI-Y/MOI-Z and CG-Z. The definition and measurement for CG-Z of a golf club head can be found in the earlier discussion relating to FIG. 2 of the accompanying drawings, while the background information establishing MOI-Y and MOI-Z have already been discussed previously. Similar to the previous discussion, the relationship between MOI-Y and MOI-Z is indicative of the ability of a golf club to achieve great forgiveness along the MOI-Y axis, while minimizing the MOI-Z of a golf club head to achieve a higher ball speed, as previously discussed. Similar to previous discussion, FIG. 11 of the accompanying drawings shows that the present invention is capable of achieving performance characteristics that was previously unachieved. This portion of the graph is delineated from other prior art data points by an equation Y≥11.349×−175.76, which when put into context with the variable used in this plot, yields Eq. (8) below:

$\begin{matrix} {\frac{{MOI} - Y}{{MOI} - Z} \geq {\left( {{11.349*{CG}} - Z} \right) - 175.76}} & {{Eq}.\mspace{14mu} (8)} \end{matrix}$

FIG. 12 of the accompanying drawings establishes another graphical relationship of a golf club in accordance with an embodiment of the present invention by creating a relationship between the (MOI-X+MOI-Y)/MOI-Z and CG-Z. The definition and measurement for CG-Z of a golf club head can be found in the earlier discussion relating to FIG. 2 of the accompanying drawings, while the background information establishing MOI-X, MOI-Y, and MOI-Z have already been discussed previously. Similar to the previous discussion, the relationship between MOI-X, MOI-Y, and MOI-Z is indicative of the ability of a golf club to achieve great forgiveness along both the MOI-X and MOI-Y axes, while minimizing the MOI-Z of a golf club head to achieve a higher ball speed, as previously discussed. Similar to previous discussion, FIG. 12 of the accompanying drawings shows that the present invention is capable of achieving performance characteristics that was previously unachieved. This portion of the graph is delineated from other prior art data points by an equation Y≥18.67×−296.63, which when put into context with the variable used in this plot, yields Eq. (9) below:

$\begin{matrix} {\frac{\left( {{MOI} - X + {MOI} - Y} \right)}{{MOI} - Z} \geq {\left( {{18.67*{CG}} - Z} \right) - 296.63}} & {{Eq}.\mspace{14mu} (9)} \end{matrix}$

FIGS. 13 through 15 show different exploded and cross-sectional view of golf club heads and their internal components that are used to achieve the performance characteristics described above. FIG. 13 shows an exploded perspective view of an exemplary design of a golf club head 1300 in capable of achieving the performance characteristics previously discussed. The golf club head 1300 is made out of the essential components previously discussed in FIG. 1 in terms of a frontal portion 1304 and a rear portion 1306. However, this exploded view of golf club head 1300 allows additional components to be shown in more detail. More specifically, FIG. 13 illustrates that, as often the case in a golf club head construction, the frontal portion 1302 may further be comprised out of a separate component called the striking face insert 1320 to form the striking portion of the golf club head 1300. The rear portion 1306 of the golf club head 1300 is where it gets more interesting. In order to achieve the performance numbers above of a higher MOI-Y, a higher MOI-X, and a lower MOI-Z, a significant amount of mass is re-allocated towards the center of the golf club head away from the perimeter. In order to achieve this, the present invention utilizes four weighting members that are all comprised out of a high density material that have a higher density than the frontal portion 1302 or the rear portion 1306. The four weighting members can be separated into a frontal sole weight 1322, frontal internal weight 1324, rear internal weight 1326, and rear sole weight 1328, and these weighting members may all generally have a material density of greater than 13 g/cc, more preferably greater than about 15 g/cc, and most preferably greater than about 17 g/cc.

It should be noted that in this exemplary embodiment of the present invention, all of the weighting members 1322, 1324, 1326, and 1328 are all made out of the same material having the same heavy density discussed previously. However, in alternative embodiments of the present invention, different densities of tungsten may be used for different weighting members depending on the design criteria and desired CG location all without departing from the scope and content of the present invention.

FIG. 14 of the accompanying drawings shows a cross-sectional view of a golf club head 1400 in accordance with an exemplary embodiment of the present invention. The cross-sectional view of the golf club head taken across a horizontal plane across the face of the golf club head 1400 to allow some of the relationship between the golf club head 1400 and the various weighting member 1422, 1424, 1426, and 1428 to be shown more clearly. In addition to the weighting members, the cross-sectional view of the golf club head 1400 shown in FIG. 14 also allows the face center 1402 and the CG location 1410 to be re-introduced as it relates to the weighting members. It can be seen from this view that at least one weighting member is located near a central portion of the golf club head in a heel to toe direction, and substantially in line with and behind said face center.

FIG. 15 of the accompanying drawings shows a cross-sectional view of a golf club head 1500 in accordance with an exemplary embodiment of the present invention taken along a vertical plane that passes through the center of the face. This cross-sectional view of the golf club head 1500 shown in FIG. 15 provides a little more information on the interworking relationship between the components. More specifically, FIG. 15 shows a striking face insert 1520 being located in the frontal portion 1504 of the golf club head 1500. In addition to the above, FIG. 15 also shows that the frontal sole weight 1522 is located in a receptacle that is created within the frontal portion 1504. Although not shown in this cross-sectional view in FIG. 15, the frontal internal weight is also located in the frontal portion 1504. Attached to the rear of the frontal portion 1504 is the rear portion 1506. The rear portion 1506 forms the aft body portion of the golf club head 1500, and contains the rear internal weight 1526 and the rear sole weight 1528. These weighting members, combined with the unique materials used to form the frontal portion 1504 and the rear portion 1506, allow the golf club head 1500 to achieve the unique performance characteristics outlined previously.

FIGS. 16 through 20 show various perspective and cross-sectional views of a golf club head 1600 in accordance with an alternative embodiment of the present invention that is capable of achieving the performance goals previously mentioned. Similar to the previous embodiment illustrated by FIGS. 1-3 and 13-15, a lot of weighting member is located near the center of the golf club head 1600 in a heel to toe orientation along the x-axis behind the face center 1602 to help minimize the MOI-Z of the golf club head 1600.

More specifically, FIG. 16 of the accompanying drawings shows a perspective view of a golf club head 1600 in accordance with this alternative embodiment of the present invention. Although not much can be gleamed from this perspective view of the golf club head 1600, it does lay the ground work for the subsequent discussion relating to this particular embodiment of the present invention. Finally, FIG. 16, similar to previous figures that illustrate a golf club head, provides a coordinate system 1601 to guide the subsequent discussions.

FIG. 17 of the accompanying drawings shows a top view of a golf club head 1600 in accordance with this alternative embodiment of the present invention. In this top view, a couple of familiar dimensions are reintroduced here. First and foremost, the top view of the golf club head 1600 shown in FIG. 17 allows the relationship between the face center 1602 and the CG 1610 to be shown in more detail. When measured along the Z-axis, the measurement CG-Z is shown as 1612. The location of the CG, when referenced against the shaft axis 1615 yields another way to measure the CG location along the Z-axis called CG-C 1614. The number ranges for the CG-Z 1612 and CG-C 1614 measurements are not much different from previous discussions, but this embodiment of the present invention provides an alternative way to achieve those targets with a slightly different construction without the need for a multi-material chassis.

FIG. 18 of the accompanying drawings shows a frontal view of a golf club head 1600 in accordance with this alternative embodiment of the present invention. In this frontal view, we can see another feature utilized by the present embodiment to help achieve the performance criteria of the current invention. More specifically, FIG. 18 shows that in this embodiment of the present invention, in order to minimize the MOI-Z of the golf club head 1600, weight is removed from the extremities of the golf club head 1600 via a reshaping of the contour at the toe portion of the golf club head 1600. This reshaping of the contour at the toe portion of the golf club head 1600 not only removes weight from the extremities, but also tightens up the face profile of the golf club head 1600 to create a unique performing golf club head 1600.

In addition to illustrating this toe contour profiling, FIG. 18 also shows a CG-B 1616 measurement relating to the shaft axis 1615 similar to the previous discussion. Once again, the CG-B 1616 measurement range is in line as the previous discussion have mentioned, and does not deviate much from the design intent of the present invention.

FIG. 19 of the accompanying drawings shows a cut open cross-sectional view of a golf club head 1600 in accordance with this alternative embodiment of the present invention taken along a horizontal plane. In this embodiment of the present invention, the overarching theme of placing the weights along the central portion of the golf club head 1600 reemerges again. More specifically, the golf club head 1600 further comprises of a frontal internal weight 1624 and a rear internal weight 1626. These weights, however, different from prior embodiments of the present invention in that they can be made out of the same material as the body portion of the golf club head 1600 such as titanium and be directly cast into the body without departing from the scope and content of the present invention. These weighting members 1624 and 1626 may also be made out of a tungsten type material having a total weight of 20-23 grams to further improve the performance of the golf club head 1600 without departing from the scope and content of the present invention.

FIG. 20 of the accompanying drawings provides another cross-sectional cut open view of the golf club head 1600 in accordance with an alternative embodiment of the present invention taken along a vertical plane. Once again, the measurements here are very similar to the discussion previously relating to prior embodiments and the CG-Z 1612 number remain within the same range as the prior discussion. This cross-sectional cut open view of the golf club head 1600 taken along this line allows the profile and geometry of the frontal internal weight 1624 and the rear internal weight 1626 to be shown more clearly and their relationship together with the body portion of the golf club head 1600.

Other than in the operating example, or unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages such as those for amounts of materials, moment of inertias, center of gravity locations, loft, draft angles, various performance ratios, and others in the aforementioned portions of the specification may be read as if prefaced by the word “about” even though the term “about” may not expressly appear in the value, amount, or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the above specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Furthermore, when numerical ranges of varying scope are set forth herein, it is contemplated that any combination of these values inclusive of the recited values may be used.

It should be understood, of course, that the foregoing relates to exemplary embodiments of the present invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims. 

1. A golf club head comprising: a frontal portion further comprising a striking face that helps define a face center, located at a forward portion of said golf club head; a rear portion located aft of said striking face; and at least one first weighting member located near a central portion of said golf club head in a heel to toe orientation, substantially in line with and behind said face center; wherein an x-axis is defined as a horizontal axis tangent to a geometric center of said striking face with the positive direction towards a heel of said golf club head, a y-axis is a vertical axis orthogonal to said x-axis with a positive direction towards a crown of said golf club head, and a z-axis being orthogonal to both said x-axis and said y-axis with a positive direction towards said frontal portion of said golf club head, and wherein said golf club head has a moment of inertia about said y-axis (MOI-Y) and moment of inertia about said z-axis (MOI-Z), and said golf club head has a MOI-Y to MOI-Z ratio of greater than about 1.50.
 2. The golf club head of claim 1, wherein said golf club head has a MOI-Y to MOI-Z ratio of greater than about 1.57.
 3. The golf club head of claim 2, wherein said golf club head has a MOI-Y to MOI-Z ratio of greater than about 1.68.
 4. The golf club head of claim 1, wherein said golf club head has a MOI-Z measurement of less than about 268 kg-mm², and wherein said golf club head has a MOI-Y measurement of greater than about 420 kg-mm², and wherein said golf club head has a moment of inertia about a shaft axis (MOI-SA) measurement of less than about 850 kg-mm².
 5. The golf club head of claim 1, wherein if said MOI-Y number is greater than about 500, said MOI-Z number is governed by the equation; MOI-Z≤(0.47*MOI-Y)+33.
 6. The golf club head of claim 1, wherein said golf club head has a moment of inertia about said x-axis (MOI-X), and said golf club head has a MOI-X to MOI-Z ratio of greater than about 1.10.
 7. The golf club head of claim 6, wherein said golf club head has a MOI-X to MOI-Z ratio of greater than about 1.20.
 8. The golf club head of claim 7, wherein said golf club head has a MOI-X to MOI-Z ratio of greater than about 1.28.
 9. The golf club head of claim 8, wherein said golf club head has a MOI-Z measurement of less than about 268 kg-mm², and wherein said golf club head has a MOI-X measurement of greater than about 320 kg-mm², and wherein said golf club head has a moment of inertia about a shaft axis (MOI-SA) measurement of less than about 850 kg-mm².
 10. The golf club head of claim 1, wherein said golf club head further comprises a second weighting member located near a central portion of said golf club head along a heel to toe orientation, substantially in line with and behind said face center, and located rearward of said first weighting member.
 11. A golf club head comprising: a frontal portion further comprising a striking face that helps define a face center, located at a forward portion of said golf club head; a rear portion located aft of said striking face; and at least one first weighting member located near a central portion of said golf club head in a heel to toe orientation, substantially in line with and behind said face center; wherein an x-axis is defined as a horizontal axis tangent to a geometric center of said striking face with the positive direction towards a heel of said golf club head, a y-axis is a vertical axis orthogonal to said x-axis with a positive direction towards a crown of said golf club head, and a z-axis being orthogonal to both said x-axis and said y-axis with a positive direction towards said frontal portion of said golf club head, and wherein said golf club head has a moment of inertia about said x-axis (MOI-X), a moment of inertia about said z-axis (MOI-Z), and CG-Z numbers that satisfies the equation below; $\frac{{MOI} - X}{{MOI} - Z} \geq {\left( {{6.7501*{CG}} - Z} \right) - {99.30.}}$
 12. The golf club head of claim 11, wherein said golf club head has a moment of inertia about said y-axis (MOI-Y), MOI-Z, and CG-Z numbers that satisfies the equation below; $\frac{{MOI} - Y}{{MOI} - Z} \geq {\left( {{11.349*{CG}} - Z} \right) - {175.76.}}$
 13. The golf club head of claim 12, wherein said golf club head has MOI-X, MOI-Y, MOI-Z, and CG-Z numbers that satisfies the equation below; $\frac{\left( {{MOI} - X + {MOI} - Y} \right)}{{MOI} - Z} \geq {\left( {{18.67*{CG}} - Z} \right) - {296.63.}}$
 14. The golf club head of claim 13, wherein said golf club head has a MOI-Z measurement of less than about 268 kg-mm², wherein said golf club head has a MOI-Y measurement of greater than about 420 kg-mm², wherein said golf club head has a MOI-X measurement of greater than about 320 kg-mm², and wherein said golf club head has a moment of inertia about a shaft axis (MOI-SA) measurement of less than about 800 kg-mm².
 15. The golf club head of claim 14, wherein said golf club head has a CG-Z measurement of between about 25 mm and about 40 mm.
 16. The golf club head of claim 15, wherein said golf club head has a CG-Z measurement of between about 26 mm and about 38 mm.
 17. The golf club head of claim 16, wherein said golf club head has a CG-Z measurement of between about 27 mm and about 36 mm.
 18. The golf club head of claim 11, wherein said golf club head further comprises a second weighting member located near a central portion of said golf club head along a heel to toe orientation, substantially in line with and behind said face center, and located rearward of said first weighting member.
 19. The golf club head of claim 18, wherein said frontal portion is made out of a first material having a first density, wherein said rear portion is made out of a second material having a second density, wherein said first weighting member and said second weighting member are both made out of a third material having a third density, and wherein said third density is greater than said first and said second density.
 20. The golf club head of claim 19, wherein said first density is greater than said second density. 